Optical Wavelength Conversion Device

Abstract

In a nonlinear optical element, wavelength conversion efficiency is degraded by the heat generation caused when high-intensity converted waves are generated. Therefore, the present invention provides a wavelength conversion optical element that includes a periodically poled waveguide. In the wavelength conversion optical element, the periodically poled waveguide includes: a core that performs wavelength conversion on a fundamental wave that has entered the entrance end, and emits a converted wave from the exit end; and a cladding that covers the periphery of the core, and the structure of the element gradually changes so as to achieve quasi phase matching from the entrance end toward the exit end in the periodically poled waveguide.

1 . A wavelength conversion optical element comprising a periodically poled waveguide,
 wherein the periodically poled waveguide includes:
 a core that performs wavelength conversion on a fundamental wave that has entered an entrance end, and emits a converted wave from an exit end; and 
 a cladding that covers a periphery of the core, and 
 a structure of the element gradually changes to achieve quasi phase matching from the entrance end toward the exit end in the periodically poled waveguide. 
   
     
     
         2 . The wavelength conversion optical element according to  claim 1 , wherein the periodically poled waveguide has a structure in which a length of a region in which polarization is set in one direction in an optical axis direction of the periodically poled waveguide gradually changes in a direction from the entrance end toward the exit end. 
     
     
         3 . The wavelength conversion optical element according to  claim 1 , wherein the periodically poled waveguide has a structure in which
 a length of a region in which polarization is set in one direction in an optical axis direction of the periodically poled waveguide is constant, and   a width of the core oriented perpendicularly to the optical axis direction gradually changes in a direction from the entrance end toward the exit end.   
     
     
         4 . The wavelength conversion optical element according to  claim 1 , wherein a refractive index of the periodically poled waveguide gradually changes in a direction from the entrance end toward the exit end. 
     
     
         5 . The wavelength conversion optical element according to  claim 4 , wherein a composition ratio of a material used in the periodically poled waveguide gradually changes in the direction from the entrance end toward the exit end. 
     
     
         6 . The wavelength conversion optical element according to  claim 4 , wherein a material used in the periodically poled waveguide gradually changes in the direction from the entrance end toward the exit end. 
     
     
         7 . The wavelength conversion optical element according to  claim 1 , wherein the cladding includes an air layer.